Decreasing contralateral prophylactic mastectomy rates in average-risk women with unilateral breast cancer.

Background: Contralateral prophylactic mastectomy (CPM) is not recommended for average-risk women with breast cancer due to lack of evidence for survival benefit, yet recent studies demonstrate increasing CPM rates.

Methods: We identified patients with breast cancer treated with unilateral mastectomy (UM) with or without CPM. Rates of malignancy in CPM specimens and factors in CPM rates were assessed.

Results: From 2013 to 2017, 1353 patients had UM and 355 had CPM. Our institution's occult malignancy detection rate was 5.04%. CPM rates decreased from 31.6% to 17.3% (p < 0.001) over 5 years. Compared to patients receiving UM only, patients receiving CPMs had significantly higher reconstruction rates (p < 0.001), which did not significantly change over time (p = 0.551) and tended to be younger (p < 0.001).

Conclusions: Patients having UM have low risk of contralateral malignancy. CPM is associated with younger age and breast reconstruction, suggesting factors to identify for patient and provider education.